What Is Solar Power Made Of?

Solar power is the conversion of energy from sunlight into electricity. It is considered a renewable energy source because the sun’s energy is virtually limitless and will continue shining for billions of years. Humans have harnessed solar power for centuries, initially using passive solar techniques like orienting buildings or openings to the sun. Active solar power generation began in the 1860s with early solar-powered engines. The modern photovoltaic (PV) solar cell was developed in 1954 to convert sunlight directly into electricity.

Interest and investment in solar power accelerated rapidly starting in the 2000s as concerns about climate change and dependence on fossil fuels grew. Solar is an important part of the renewable energy transition because it produces no greenhouse gas emissions during operation and has enormous scalable potential. As of 2020, solar accounted for about 3% of total U.S. electricity generation. Many experts project that solar power, especially PV technology, will continue experiencing substantial growth and provide over 20% of global electricity by 2030.

Solar power offers many benefits in addition to its renewable nature. It can help improve public health by reducing air pollution from fossil fuel combustion. Solar systems can be installed rapidly and modularly almost anywhere sunlight is available. Improvements in efficiency and materials are also making solar power increasingly cost-competitive with conventional power sources. However, intermittency, land use, and storage remain challenges to greatly increasing solar penetration. Overall, solar power is an essential technology for building a more sustainable energy system.

Photovoltaic Solar Panels

photovoltaic solar panels convert sunlight directly into electricity

Photovoltaic (PV) solar panels are the most common type of solar panel. They work by directly converting sunlight into electricity through the photovoltaic effect. PV panels are made up of many solar cells containing a photovoltaic material, usually silicon.

When sunlight hits the solar cells, the energy from the photons in the light knocks electrons loose from the atoms in the photovoltaic material. Electrons freed by the photovoltaic effect flow through the material to produce an electric current. This electricity generated can then be used to power electrical loads.

PV panels have no moving parts and require very little maintenance. They can last over 20 years. Their biggest advantage is the ability to produce electricity directly from sunlight without any additional mechanical components.

The efficiency of a PV panel determines how much of the sun’s energy striking the panel is converted into usable electricity. Most silicon PV panels on the market today have efficiencies between 15-22%. Higher efficiency panels produce more electricity, but also tend to be more expensive.

Solar Cell Materials

The most common material used in solar cells is silicon (https://www.energy.gov/eere/solar/solar-photovoltaic-cell-basics). Silicon solar cells can be classified into two main types: monocrystalline silicon and polycrystalline silicon. Monocrystalline silicon is a single continuous crystal, which results in higher efficiency but is more expensive. Polycrstyalline silicon is made up of multiple crystals, resulting in a lower efficiency but a lower cost (https://www.homeowner.com/solar/solar-cells-guide).

Some other common semiconductor materials used in solar cells include germanium, gallium arsenide, cadmium telluride, and copper indium gallium selenide. Gallium arsenide solar cells have a very high efficiency but are expensive. Cadmium telluride is a thin-film solar cell material that is lower cost but less efficient than silicon. Copper indium gallium selenide (CIGS) is another thin-film solar cell material that has emerged as a low-cost option (https://g2voptics.com/photovoltaics-solar-cells/solar-cell-materials/).


Solar panels are encapsulated to protect the sensitive solar cells inside from the elements and other potential damage. The main components of encapsulation are:

Protective Glass

The top layer is a sheet of low iron, tempered glass that allows sunlight to pass through while protecting against impact, weather, and UV rays (Source 1).

Polymer Encapsulant

Under the glass is a layer of polymer encapsulant, usually EVA (ethyl vinyl acetate). The encapsulant seals and cushions the solar cells (Source 2).

Weatherproof Backing

On the bottom is a weatherproof backing sheet, typically made of tedlar or polyvinyl fluoride film, to protect against moisture, humidity, and other environmental factors.


The frame provides structural support and protection for the solar cells and other components inside a solar panel. Most solar panel frames are made from aluminum, especially anodized or powder coated aluminum. Anodized aluminum is a popular choice because the anodizing process creates a protective oxide layer that makes the metal highly durable and resistant to corrosion (https://aluminumsolarframe.com/what-material-is-used-in-frame-of-solar-panel/).

Aluminum is lightweight, strong, and affordable, making it an ideal metal for solar panel frames. The frame surrounds the perimeter of the panel to hold the glazing, backing material, and solar cells in place. Aluminum’s strength allows it to protect the inner components from damage due to impacts, wind, or other external forces. Its corrosion resistance ensures the frame maintains integrity over decades exposed to outdoor environments. Stainless steel may also be used in areas that require additional structural reinforcement.

Junction Box

The junction box of a solar panel is an essential component that houses the electrical connections of the solar cells. According to Solar Power World, the junction box plays a simple but crucial role in protecting these connections from the environment.

The junction box is usually located on the back of the solar panel. Inside the junction box, the individual solar cells are electrically connected to each other. Thin wires are soldered between the cells to create strings of cells. The junction box collects all of these string connections into a single output cable.

This allows the DC electricity generated by the solar cells to be combined into a single output that can then be sent to an inverter or charge controller. The junction box provides a protective housing for these delicate electrical connections, shielding them from weather, dirt, and other environmental factors that could cause issues.

Junction boxes are made of durable plastic or metal and have gaskets and seals to prevent moisture ingress. They contain terminals to connect the outgoing wires from the panel and may also integrate bypass diodes to maximize power output. Overall, the junction box allows the DC electricity from all the solar cells to be consolidated safely for further use.


The wiring in solar panels is responsible for conducting the electricity generated by the solar cells to the other components of the system like batteries or inverters. Copper is the most commonly used material for solar panel wiring due to its high conductivity and flexibility. Solid copper wires with PVC insulation are generally used.

The size of the copper wires (gauge) depends on factors like the power output of the solar panels and the length of the wire runs. Typically 10-12 AWG gauge copper wires are used for standard residential solar installations. The positive and negative terminals of each solar panel are connected to these copper wires to form a ‘string’ of panels.

Proper wiring helps minimize power losses as electricity travels from the solar panels to the batteries for storage. Thicker copper wires with lower gauge help reduce resistance and transmit more power efficiently. The wires are color coded (red for positive, black for negative) for easy identification and troubleshooting. Careful wiring by professional installers ensures safety, performance and longevity of the solar system.



Connectors are used to join together the wiring of solar panels and other system components. The most popular type of connector used today is the MC4 connector. MC4 stands for “Multi-Contact 4” and refers to the 4 points of contact between the male and female connectors.

MC4 connectors are weatherproof and safe for outdoor use, which makes them ideal for solar applications. They feature a snap-together design that creates a secure, waterproof connection between cables. The connectors are also polarized, meaning they can only be connected in one direction, avoiding reversed polarity and other issues.

The MC4 is considered an industry standard for solar installations. Nearly all modern solar panels come with pre-attached MC4 cables for plug-and-play connections. They are also backwards compatible with older MC3 connectors in most cases.

Overall, MC4 delivers a reliable, long-lasting connection that minimizes points of failure in a solar system. Its popularity and ubiquity make it easy to safely “snap” components together for fast solar installations and upgrades.


Solar panels produce direct current (DC) electricity, while homes and the utility grid use alternating current (AC) electricity. Therefore, solar systems require controllers to convert DC to AC power and regulate energy output. The main functions of solar controllers include:

  • Regulating voltage and current to protect batteries from overcharging. Controllers prevent batteries from being damaged by limiting how much electricity is fed into them.
  • Converting DC electricity from solar panels into AC electricity for home use and synchronizing with the grid. This allows excess solar energy to be fed back into the grid.
  • Maximizing energy harvest by tracking the maximum power point of panels. MPPT controllers optimize efficiency.
  • Providing safety features like ground fault and arc fault circuit protection.
  • Enabling remote monitoring and control of the solar system.

By regulating power output, controllers allow solar systems to safely integrate with batteries and the utility grid. Common types of controllers include MPPT, PWM, and grid-tied inverters. Controllers range from simple to advanced devices with internet connectivity and metering abilities.


Solar power has seen tremendous growth and innovation over the past decade. The future continues to look bright for this renewable energy source. Improvements in solar cell efficiency, energy storage technology, and manufacturing processes will enable solar to become an increasingly cost-competitive energy solution. With supportive government policies and declining costs, solar is poised to play a major role in the global transition to clean energy.

Looking ahead, we can expect solar to account for an ever greater share of electricity generation worldwide. As solar energy storage improves, solar will become a more viable option for meeting peak energy demands. New solar cell technologies currently in development hold promise to push efficiencies even higher. Emerging thin-film solar materials offer potential for flexible, lightweight solar panels. Concentrated solar power plants with thermal energy storage can provide dispatchable renewable energy around the clock. While challenges remain, the future is bright for solar photovoltaics to supply a substantial portion of the world’s electricity needs.

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